“We must build up, not out,” said Soleri. “The problem is the present design of cities are only a few storeys high, stretching outward in unwieldy sprawl for miles…turning farms into parking lots, and waste enormous amounts of time and energy transporting people, goods and services over their expanses.”

For obvious reasons, Paolo Soleri’s plans for kilometre-high megastructure cities towering over green landscapes were popular in science fiction books and magazines in the 1970s. Soleri’s solution to unstoppable urban sprawl seems eminently sensible despite the difficulties of building anything on this scale; complaints about undesirability can be countered (in Britain at least) with dismal stories such as this recent report. Or maybe it’s better to live in a Hong Kong shoebox? Soleri devoted most of his life to thinking about how architecture could better serve our limited planetary resources; with Arcosanti he was leading by example.